Spark gap



June 17, H H, Q B N 1,764,279

S PARK GAP Filed May 15, 1925 4 Sheets-Sheet 1 June 17, 1930. H. H. OSBORN SPARK- GAP Filed May 15 1925 4 Sheets-Sheet H. H. OSBORN SPARK GAP June 17, 1930.

4 sheets -sheet 5 317/?1'2202 3- W C 6M Filed May 13 1925 May/51.1-

Patented June 17, 1930 v UNITED STATES PATENTOFF C HOWARD H. osBomv; or cHIoAGo,- 1I;LmoIs, ASSIGNOR T0 n. eqriscnnn a. 00., or cmcneo, rumors; AooRroRArroN or ILLINOIS sum: 0A3

' hpplicat ionjfiled ma 13, 925. Serial No. 29,897.

This invention relates in general to spark gaps, and more particularlyjto that type of device adapted for use in electrothereapeutic apparatus and the like.

5 An important object of the invention is the provision of a spark gap which may be adjusted in substantially infinite degrees from zero capacityof the device tomaximum capacity of the device in order to fag cilitate accurate control of the current flow. Another important object is the provision of a spark gap which insures against sudden change in the current passingthe gap as is common in devices provided heretofore 5 which have tap switches or similar means 7 for connecting in or shunting outfixed spark gaps. With such devices, it is undesirable to vary the current during a treatment, because of the resulting severe shock to the Opatient. V

Another important object of the invention is the provision compact spark gap device comprising a plurality of individual spark gaps connected in aseries'circuit, the 5 operativeparts of which however are amply spaced to prevent arcing and'which are ar: ranged relatively in such a manner that the magnetic fields, generated at the individual spark gaps upon discharge of the device, 0 counter-act and nullify each other and create a balanced resultant magnetic field, thus preventing the production'of any. appreciable magnetic effect by the device when in operation.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the'follow'ing description, which, taken in connection'withthe accom-.

bodiment thereof.

Referring to the drawings V Figure 1 is a side elevation of a device embodying my invention;

Fig. 2 is a top plan view thereof;

Fig. 3 is a bottom plan view thereof;

Fig. 4 is a section taken substantiallyon line H in Fig. 1;

Fig. 5 is a section taken'substantiall'y on line 5--5 in Fig. 1; and" v panying drawings, discloses a preferred em- Fig. 6 is a section taken substantially on line 6 6 in Fig. 4:...

To illustrate my invention I have shown on the drawings a pair of frame members 11 and 12 comprising bars of suitable nonconducting material yieldably secured together as at 14 by means of posts 51, 52 and 53 formed integrally with the upper frame member" 12 and extending to adjacent the lower franie member.- A pluralityof fixed electrodesjlti, 16, 17 and 18having upwardly disposed tips are supported-from the frame member 11 on one'side thereof and are arranged in along the, rame' member by means of strips parallelism in spaced relationship of conducting'material 68 comprising supporting members wh ch engagethe upper and lower sides of thesframe member 11 and extend therefrom and engage the electrodes to support them in :position. Similar electrodes 21, 22, 23 and 24 are similarly supported from the, frame 'member 11 on ,the

opposite side thereof andeach is preferably disposed directly opposite a corresponding one of the electrodes 15, 16, 17fand 18, to I provide asymmetrical arrangement of the electrodes. Adjustable electrodes 25, 26,27

and28, having downwardly disposed tips are supported from the upper frame member 12 on one side thereof and'a-re arranged in registerlng alignment with the lower fixed elec-- trodes 15, 16, 17 and 18, and similar elec trodes 31,32, 33 and 34 are supported on the opposite side of the frame member 12 oppo site the electrodes 25, 26, 27 and 28 and in registering alignment with the lower fixed electrodes 21, 22, 23 and 24 by means of supporting strips 78' which engage the upper andlowerfaces of the frame member and extend"v therefrom to' embrace and support the electrodes in assembled posi-tion. An adjustable handle 35*isprovided to vary the spacing of the frame members 11 and 12 and thereby control the width of the spark gaps formed between the tips of the adi'u'stable 1 and fixed electrodes. Terminal brac Gt-S are preferably provided at opposite ends of the frame member 11 for mounting the' device in a high frequency apparatus or the like, and in the present instance, I have shown viding suitable electrical contapt forconnect ing the device in a circuit.

The frame member 11 is or may be ofanyJ suitable insulating material of sufficient length, and is preferably square or rectangular in cross. section, Shoulder; studs 44 having an enlarged portion 45-aresecured to the frame member 11, havingabearingat 46. Two or more of these, shoulder studs are preferably provided andspacect an equal distance on opposite sides of the center; of the frame member l1 Spaces are formed in the frame member 11 above the enlarged portionv 4 5,, of the shoulder stud, 44 toprovide'a suitable housing, for the lower end of a. spring 47. A stud 48 having an enlarged portion 49 engages. an aperture through the mid portions of the frame memberlli. The frame member 12 is also preferably of inuli t ng. ma e i Lis qu n L ng t the frame member 11' and is 'substantiallyree tangular in cross section having, av plurality of depending bearing lugs 51, '52 and 53 positioned in alignment. with studs 44. and 48.; The lugs 51; and 53 are apertured as at 54 to receive and, provide a-[free sliding fit for the studs .44. and counterbored. as at 55 to provide a housing for the upper end. of the spring 47, which normally tends to separate the frame membersll and 12i The lug 52 is apertured at. 56. to provide a free. sliding lit for the. stud; 48 and. may be counter-bored as at 57 toprovide clearance for the enlarged portion 49 of thestud. 48. Separating movement of the frame members 11 and 12'is limited by threadedv caps 58 engaging the threaded. end of the studs 44,

which protrude above the i u per: surface ofthe frame. member 12. T e adjusting handle 35.- is. formed of insulating material and has. a threaded bushing. 59 moulded therein for engaging the threadedyend of the stud 48 whichfpnotrudesabovethe upper surface of theframemember. 12. A washer 61 is preferably, placed between. the adjusting handle 35 and frame member 12 to r d c i ioa. t. .W L t s. be n te ha rotation. of the. operating handle 35. in.one re io t rcss h amememb r- 12 w r thefframe member 11 against the compress i n, ot he pr ns and ta i n, n he. pposite din tiQn' P rmits he spri gs to epa a e. t ramemembe s Ha il- 2 d t ry th en betw en. he everal: el clrqdee The fixed electrodes 15 to 18 and 21 to 24 inclusive are formed from a suitable conducting material and each comprises a shoulder pin 62 of sufiicient length to extend through the supportin strips 68 which are secured to opposite sides of the frame member 11 and. which are apertured for the purpose. The pin 62 is threaded at 63 to. receive a nut 64 by which pin is secured in position; throughflthe apertured supporting stri s68. A portion 65 of the pin 62 exten s upwardly to form a contact member having a platinum or other suitable contact point suitably secured thereon. The tips of the fixed electrodes are disposed in a plane intermediate theframe members 11 andi12. A plurality of. annular radiating fins- 66. are. positioned over the. pin 62, and between the links 68. for cooling the electrode.

The. adjustableelectrodes 25to 28 and 31 to. 34. inclusive are formed ofsnitable con- I ducting material and are supported in. any

suitable manner providing;longitudinal adjustment of each electrode, in order that the fixed and movable electrodes may be spaced adjustably apart to provide spark gaps t-herebetw'een. In t-he present instance, I have shown fscrewthreaded electrodes 71 each provided with. a platinum or other suitable contactdpoint secured to. a lower end thereof and a control handle 73 secured to the opposite. upperaend of the. electrode. A- bearing sleeve. 74 having an internal threaded portion 75 adaptedto threadingly engage. thev electrode .71 and having an enlargedshoulder .76, at the upper end and an externally threaded. portion 77 at'the lower end, is. arranged; to, support each. electrode. in pl ce- Thebe r ng eY 4has suf i e t length. to. extend through, a pair of. support-. ing strips. 78 whichjare secured. to the opposite. sides. of thenframe. member 12 and whichv are. apertured. to. accommodate the bearing sleeve 74. Aplurality of annular radiating fins 79 which providea means. for spacing the supportingstrips7 8 apart are assembled externally upon thebearingsleeve between the strips. The shoulder 76 is adapted to engage th upper of the supportingstrips. 7 8 and upon assembly is secured in place by means ofja nut 81 engaging the threaded portion 77 at the bottom end of the sleeve and engaging the lower of thesupporting strips 78. A second threaded nut 82 having internal threaded engagement with. the electrode 71 and external sliding engagement with the bearing sleeve 74 and having a. depending finger 83 adapted to engage. a recess or aper ture 84in the upper of. the supporting strips 78 is provided; at the topyof the spacing sleeve 74, and an annular spring 85 having anorma l upward pressure, is arranged in a pocket 86 at the upper endgof the. spec,

.ing sleeve 74 and provides, frictionalen-i gagement therewith to prevent rotation of the electrode 71 such as may be caused by vibration of the device set up by the discharge of electrical current across the spark gaps.

The supporting strips 68 and 78 for the adjustable electrodes are electrical conductors and provide electrical connection between adjacent electrodes. The spark gaps formed between the" spaced ends .0f co-op-.

by means of the diagonal connecting strips 68, and the adjacent electrodes 16 and.17

are electrically connected and-supportedin position'by' a v shaped connector. The up per and lower electrodes are each connected electrically to a diametrically opposed electrode, electrode 25 bein connected to 31, 15 to 22,- 32 to 26, 16 to 1 27 to 33,18 to 23 and 28 to 34 by means of the transverse connecting strips 7 8. All the spark gaps formed between cooperating electrodes are thus arranged in series and the spark gap circuit extends from a terminal support 42 through the short support strip 68 to the lower electrode 21 andupthrough a spark gap to the co-operating upper electrode 31, thence across the device through one of the cross connectors 78 to the diametrically disposed electrode 25 and down through a gap to the cooperating lower electrode 15, thence diagonall through one of the long strips 68 to the ower electrode 22and up through a spark gap to the cooperating upper electrode 32 thence across the device through another of the cross connectors 78 to the diametrically disposed upper electrode 26 and down through a spark gap to the cooperating lower electrode 16. This somewhat spiral path of the circuit through the device now reverses. The lower electrode 16 is connected to the adjacent lower electrode 17 on the same side of the device byv means of the V-shaped connector 68 instead of to the diagonally disposed electrode 23. The circuit from the lower electrode 17 continues up through a spark gap to the cooperating upper electrode 27, thence across to the diametrically disposed electrode 33 and down through spark gap to the cooperating lower electrode 23, thence diagonally across to the lower electrode 18 and up through a spark gap to the cooperating upper electrode 28, thence across the device to the diametrically disposed upper electrode 34 and down through a spark gap to the cooperating lower electrode 24 which is connected to the other terminal support 42,

thus completing the circuit between the terminal supports.

From this description it will be noted that the spark gapslie in a plane and are sym metrically grouped? lVhen a discharge oc curs, current will flow through the spark gap circuit etween the terminal posts 42, the current travels. upwardly across the spark gaps formed between terminals 21 to 31, 22 to 32, 17 to 27 and 18 to'28, while travelling downwardly between terminals 25 to 15, 26 to 16, 33 to 2 3, and 34 to 24, and vice versa. It will also be noted that the gaps besides being arranged symmetrically are'connected electrically so that the.

magnetic fields produced by the gaps upon discharge are balanced about any axis lying in the plane of the gapsandabout which thegaps are symmetrically disposed. This arrangement provides-a non-magnetic spark gap device, in which the fields produced by the individual spark gaps counteract and nullifyeach other and substantially elim inate the possibility of magnetic disturb-z ance produced by the resultant ofthe individual fields. The nullification: of the magnetic effect is produced by grouping the'spark gaps symmetrically and byponnecting the parts electrically in such a man-. nor that f the instantaneous current flow. across the individual gaps produces "a plu-- rality' of symmetrically disposed-magnetic fields, the magnetic sum of which is stantially zero. i '7 j I It will be noted that a'slight movement ofthe operating handle 35-produces a con-. siderable'variation in the total eifective gap of the device, which comprises the'sum of the lengths of the individual gaps and'that adjustment of any of the knobs 73 whichfco'ntrol individual gap setting provides an ex} tremely finevernier adjustment. All of the operating handles are threaded" so that the changein the spark gap setting and hence in theamount of current passing through the gap may only be efiectedgradually. This feature preventssudden variations in the current which, as before noted, shock the patient. Adjustment to*accomn10date for wear or deterioration of the contact points of the electrodes arealso possible because of the adjustabil-ity ofthe electrodes.

The utility of a non-magnetic spark gap is most apparent when a spark gap is required in apparatus including delicate measuring instruments. The operation of such instruments may be seriously effected by external magnetic disturbances with the result that when ordinary spark gaps are used, it is necessary to mount the gap in a separate container positioned at a distance from the delicate instruments,,orto shield the gap in a specially constructed compartthe form hereinbefore frame member,

ment providing a magnetic shield. Such assembly is cumbersome, costly, and prvides, an inconveniently bulky apparatus. The non-magnetic spark gap obviates the necessity of shielding delicate instruments from the magnetic disturbances and allowsthe provision of compact apparatus at a correspondingly low cost of production.

Itisthought that the invention and many of its attendant advantages will be understood from the foregoing description, and it will beapparent that variouschanges may be made. in the form, construction. and arrangement of the parts without departing from the. spiritand: scope of the invention or sacrificing all. of its material advantages,

described being merely apreferred embodiment thereof.

\ I- claim:

1. A spark gap. device comprising a frame member, a plurality of fixed electrodes supported symmetrically from said 'frame member, a second frame member and a plurality of movable electrodes supported on said; second frame member arranged to cooperate with said fixed electrodes and having axial alignment with said fixed electrodes, spark gaps being formed betweenthe cooperating fixed and movable electrodes, means securing said. frame members 1n spaced relatlonshlp, and means for vary- I ing said relationship to provide gap adjustment between cooperating electrodes.

2. A spark gap device, comprising, a

a plurality of electrodes secured to said frame member, a second frame member, a plurality of electrodes adjustably secured to said second frame member and. arranged tocooperate with said fixed electrodes to form spark gaps therebetween,

cooperating electrodes being arranged in alignment, connectin means for connecting said first mentioned rame member and said second frame member, and means varying the} spacebetWeen said frame; members to simultaneously vary the gaps between said fixed and said adjustable electrodes.

3; A spark gap device, comprising, a frame member, a plurality of electrodes secured to said frame-member, asecond; frame member, V a, plurality of electrodes adj ustably secured to said second frame member and arranged in registering alignment with said fixed-electrodes and tog'provide spark gaps, connecting means for connecting said first mentioned frame member and said second frame member,

and means varying the space between saidframe membersto simultaneously vary the gaps between said'fixed and said adjustable electrodes, said fixedand 4. A spark gap device comprising a frame member, a plurality of fixed elec trodes secured to said frame member, a second frame member, a plurality of adjustable electrodes secured to said second frame member and arranged in registering alignment with said fixed electrodes and to provide spark gaps, connecting means for connecting. said first mentioned frame member and said second frame member, and means varyingthe space between said frame members to simultaneously vary the gaps between, said fixed and said adjustable elec trodes, said adjustable electrodes having threaded engagement in said second frame member to provide adjustment for individual spark gaps.

5. A spark gap device, comprising a plurality of pairs of spark gap electrodes, each pair comprising a fixed and a movableelectrode, means for adjusting the movable electrode of each pair toward and into contact with. its companion fixed electrode, and

means for simultaneously moving all of said movable electrodes toward and from their companion fixed electrodes.

6. A spark gap device, comprising a pair 7 HOWARD H. OSBORN.

adjustable electrodes being connected inse- 

